Diffuser-pump for marine propulsion propeller hub exhaust



April 1966 E. c. KIEKHAEFER 3,246,698

DIFFUSE RPUMP FOR MARINE PROPULSION PROPELLER HUB EXHAUST Filed March 8, 1965 i i z ZQqQ INVENTOR [ZMER (ARL IOEKHAEFER BY 5 (/ynalrus I! jldnlk United States Patent 3,246,698 DIFFUSER-PUMP FOR MARINE PROPULSION PROPELLER HUB EXHAUST Elmer Carl Kielrhaefer, Winter Haven, Fla., assignor to Kiekhaefer Corporation, Fond du Lac, Wis., a corporation of Delaware Filed Mar. 8, 1965, Ser. No. 437,788 8 Claims. (Cl. 170166) This invention relates to a diffuser-pump for the propeller hub exhaust system of a marine propulsion unit,

Heretofore outboard motors, stern drive units and the like have often included a propeller assembly with a hub through which exhaust gases are discharged into the water. The construction should be such that any water disposed within the hub is substantially fully discharged rearwardly during either forward or reverse operation of the propeller.

The present invention is based on an improvement 1n known prior structures, and generally contemplates the utilization of a removable replaceable combined diffuserpump member at the extreme discharge end of the hub. More specifically, the member is secured for rotation with the outer end of the propeller shaft and includes radial vanes integral with a flared diffuser ring which act in combination to pump water from the hub.

The accompanying drawing illustrates the best mode presently contemplated by the inventor for carrying out the invention.

In the drawing:

FIGURE 1 is a side elevation of an outboard motor embodying the concept of the invention;

FIG. 2 is an enlarged vertical axial section through the propeller assembly; and

FIG. 3 is an outer end view of the propeller assembly, with parts broken away.

As shown in the drawing, the invention is adapted for use with a marine propulsion unit such as an outboard motor 1 having an engine enclosed by a cowl 2, with the latter being supported at the upper end of a drive shaft housing 3, which in turn is connected to a lower underwater housing 4. The motors drive shaft is connected through suitable gearing to drive the rotatable propeller shaft 5 which extends rearwardly of housing 4 for supporting the propeller assembly 6.

Assembly 6 is shown as being disposed inwardly of the shaft end and comprises a generally cylindrical hub 7 having suitable propeller blades 8 extending radially outwardly therefrom. Hub 7 is adapted to be supported on shaft 5. For this purpose, a plurality of circumferen tially spaced longitudinal struts 9 extend radially inwardly from hub 7 and terminate in an annular sleeve 10. A cylindrically shaped resilient relief member 11 mounted on a suitable bushing 12 is press fit or otherwise secured concentrically within sleeve 10, with bushing 12 adapted to be mounted on propeller shaft 5, as shown. Sleeve 10 extends forwardly of member 11 and bushing 12 and engages the shoulder of an elongated spacer 13 mounted on the shaft and which in turn is adapted to normally engage a shoulder 14 on the shaft. A suitable gasket 15 may be disposed between sleeve 10 and spacer 13.

The inner end 16 of hub 7 is slightly reduced in thickness and is adapted to freely fit and rotate within an annular opening 17 in housing 4.

During operation of outboard motor 1, exhaust gases pass downwardly through housings 3 and 4 and hence through opening 17, and are discharged through the passage 18 formed between hub 7 and sleeve 10.

It is advisable to prevent accumulation of water in passage 18 so that exhaust gases are freely discharged from the hub interior. In accordance with the invention, the rearward end of the propeller assembly is pro- 3,246,698 Patented Apr. 19, 1966 vided with means to accelerate the removal of water from the hub. For this purpose, an annular diffusenpump assembly 19 is disposed at the outer hub end and is constructed to permit passage of exhaust gas therethrough.

Assembly 19 comprises a central support or washer 20 which is internally splined and thereby engages the splines 21 on the end of propeller shaft 5. A plurality of circumferentially spaced pump vanes 22 are integral with washer 20 and extend radially outwardly therefrom to a diameter approximating that of the inner diameter of the hub end. The outer ends of vanes 22 merge into an integral diffuser ring 23 having a forward diameter approximately the same as that of hub 7 and spaced therefrom. Ring 23 is shown as having a constant thickness throughout, and with inner and outer surfaces which flare outwardly in a rearward direction.

The entire assembly 19 is removably mounted on shaft 5 by a suitable nut 24 and lock washer 25. When nut 24 is tightened, the assembly serves to drive the propeller, since washer 20 engages bushing 12 on the shaft as through a suitable gasket 26 therebetween. Washer 20 has an inwardly directed flange 27 which is disposed within the outer end of sleeve 19. To accommodate tolerance variations, a space 28 may remain between hub 7 and diffuser ring 23.

The flared contour of ring 23 serves to assist in the rearward forceable removal of water from passage 18. However, positive mechanical centrifugal pumping action in the diffuser area is created by vanes 22 which force wate'r against the flared ring and thus rearwardly. In some instances, it is desirable to provide auxiliary pump ribs or vanes which are spaced circumferentially between vanes 22 and which have a radial extent substantially less than vanes 22. Those shown at 29 are integral with and extend inwardly from diffuser ring 23, although other constructions may be possible.

If desired, the outer surface of the diffuser ring 23 may be shaped and positioned to simulate the outer end of the hub construction set forth in U.S. Patent No. 2,948,252 to provide improved exhaust discharge.

The combined diffuser-pump assembly 19 may be manufactured with relative ease, since it is of single piece integral construction entirely separate from hub 7 or sleeve 10. In some instances, as where the propulsion unit is to be used for trolling, more effective pumping action may be desired. Assembly 19 may easily be removed and replaced with another assembly having a differently flared diffuser ring or different shaped pump vanes to give the desired action.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. In a marine propulsion device having a rotatable propeller shaft and a generally cylindrical hollow propeller hub mounted on said shaft, means for discharging water rearwardly from within said hub, said means comprising:

(a) radially extending centrifugal pump means connected for rotation with said shaft and disposed rearwardly of the discharge opening of said hub,

(b) said pump means including an outwardly flared diffuser connected to said pump means rearwardly of said discharge opening.

2. In a marine propulsion device having a rotatable propeller shaft and a generally cylindrical hollow propeller hub mounted on said shaft:

(a) a plurality of radially extending vanes connected to said shaft for rotation therewith, said vanes being disposed rearwardly of the rear end of said hub,

(b) and an outwardly flared annular diffuser ring carried by the outer ends of said vanes rearwardly of and adjacent the rear end of said hub,

(c) said vanes acting as a pump and cooperating with said flared diffuser ring so that water disposed within said hub is discharged rearwardly during rotation of said shaft.

3. In a marine propulsion device having a rotatable propeller shaft and a generally cylindrical hollow propeller hub mounted on said shaft and disposed inwardly of the end thereof, means disposed rearwardly of the rear end of said hub for forceably discharging water from the hub interior, said means comprising:

(a) a member secured to the outer end of said shaft for rotation therewith,

(b) a plurality of circumferentially spaced vanes extending radially outwardly from said member to approximately the inner diameter of said hub,

(c) and a diffuser ring carried by the outer ends of said vanes, said ring having a forward diameter approximately corresponding to that of said hub and flaring outwardly in a rearward direction,

(d) said vanes acting as a pump and cooperating with said ring so that water disposed within said hub is discharged rearwardly during rotation of said shaft.

4. The device of claim 3 which includes: a plurality of circumferentially spaced auxiliary pump vanes extending radially inwardly from said ring and with said auxiliary vanes having a radial extent substantially less than the said first-named vanes.

5. In a marine propulsion device having a rotatable propeller shaft and a propeller hub assembly disposed inwardly of the shaft end with said assembly including a generally cylindrical hollow hub and a central hub support mounted on said shaft:

(a) a unitary device disposed rearwardly of the rear end of said hub assembly for rearwardly discharging water from the hub interior, said device comprising:

(1) a washer mounted on the outer end of said shaft for rotation therewith,

(2) a plurality of circumferentially spaced vanes integral with and extending radially outwardly from said washer to approximately the inner diameter of said hub,

(3) and an annular outwardly flared diffuser ring integral with and disposed at the outer ends of said vanes and spaced from said hub,

(4) said vanes and ring cooperating so that water disposed within said hub is discharged rearwardly during rotation of said shaft,

(b) and means securing said unitary device upon said shaft.

6. For attachment rearwardly of the hollow propeller hub assembly mounted on the propeller shaft of a marine propulsion device, a device for forceably discharging water from the interior of the assembly, said device comprising:

(a) an annular member adapted to be secured to the end of the shaft,

(b) a plurality of circumferentially spaced pump vanes integral with and extending radially outwardly from said member,

(c) an annular outwardly flared diffuser ring integral with and disposed at the outer ends of said vanes,

(d) and means for mounting said device on said shaft and rearwardly of the hollow propeller hub assembly.

7. The device of claim 6 which includes: a plurality of circumferentially spaced auxiliary pump vanes integral with and extending radially inwardly from said diffuser ring and with said auxiliary vanes having a radial extent substantially less than the said first-named vanes.

8. A pump assembly for preventing accumulation of water in the hollow exhaust passage of the propeller hub of a marine propulsion device, said pump comprising:

(a) an annular member,

(b) a plurality of circumferentially spaced pump vanes extending radially outwardly from said member,

(c) an annular diffuser ring disposed at the outer ends of said vanes,

(d) and means for mounting said assembly rearwardly of said hub for passage of exhaust gases therethrough.

References Cited by the Examiner UNITED STATES PATENTS 2,616,511 11/1952 Perrott -l66 2,948,254 8/1960 Witt 170166 X FOREIGN PATENTS 418,881 12/1910 France.

4,718 1909 Great Britain. 162,066 4/ 1921 Great Britain.

MARK NEWMAN, Primary Examiner. 

1. IN A MARINE PROPULSION DEVICE HAVING A ROTATABLE PROPELLER SHAFT AND A GENERALLY CYLINDRICAL HOLLOW PROPELLER HUB MOUNTED ON SAID SHAFT, MEANS FOR DISCHARGING WATER REARWARDLY FROM WITHIN SAID HUB, SAID MEANS COMPRISING: (A) RADIALLY EXTENDING CENTRIFUGAL PUMP MEANS CONNECTED FOR ROTATION WITH SAID SHAFT AND DISPOSED REARWARDLY OF THE DISCHARGE OPENING OF SAID HUB, (B) SAID PUMP MEANS INCLUDING AN OUTWARDLY FLARED DIFFUSER CONNECTED TO SAID PUMP MEANS REARWARDLY OF SAID DISCHARGE OPENING. 